Vaccination of goats with a thermotolerant experimental vaccine confers a full protection against a PPR virulent challenge

Peste des petits ruminants (PPR) is an OIE-listed disease of small ruminants, endemic in Africa and Asia, causing high economic impacts. Vaccination is an effective way to control PPR, but hot ambient temperatures associated to possible power cuts in developing countries may alter the vaccine stability during storage and transportation. Thus, making available an effective and thermotolerant vaccine is a priority. Lyophilized form of an experimental vaccine (EXP-VAC), formulated to be thermotolerant, was exposed at 37°C for three days before use, mimicking a cold-chain rupture. Ten PPRV-naïve goats received a dose of well-established PPR-VACTM[1], ten others received a dose of EXP-VAC and another ten remained unvaccinated. Twenty one days later, all goats were infected intranasally with a virulent PPRV (Morocco 2008). Clinical signs and viral ocular excretion (RT-qPCR) were monitored for 14 days. Controls presented PPRV ocular shedding and severe clinical signs related to PPR such as nasal and ocular discharge, mucosa lesions, diarrhea, and weight loss. EXP-VAC-vaccinated goats only presented few mildly swollen lymph nodes. EXP-VAC completely prevented viral ocular excretion. No difference in efficacy was observed between EXP-VAC and PPR-VACTM used according to label. Thus, efficacy of EXP-VAC was demonstrated. This thermotolerant vaccine may be an aid to allow epidemiological control of PPR preventing economic losses in areas where the cold chain cannot be guaranteed